89 lines
2.9 KiB
Python
89 lines
2.9 KiB
Python
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import random
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import numpy as np
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from urh.signalprocessing.IQArray import IQArray
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from urh.signalprocessing.Message import Message
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from urh.signalprocessing.Modulator import Modulator
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from urh.signalprocessing.ProtocolAnalyzer import ProtocolAnalyzer
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from urh.signalprocessing.Signal import Signal
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def demodulate(signal_data, mod_type: str, bit_length, center, noise, tolerance, decoding=None, pause_threshold=8):
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signal = Signal("", "")
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if isinstance(signal_data, IQArray):
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signal.iq_array = signal_data
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else:
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if signal_data.dtype == np.complex64:
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signal.iq_array = IQArray(signal_data.view(np.float32))
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else:
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signal.iq_array = IQArray(signal_data)
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signal.modulation_type = mod_type
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signal.samples_per_symbol = bit_length
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signal.center = center
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signal.noise_threshold = noise
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signal.pause_threshold = pause_threshold
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if tolerance is not None:
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signal.tolerance = tolerance
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pa = ProtocolAnalyzer(signal)
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if decoding is not None:
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pa.decoder = decoding
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pa.get_protocol_from_signal()
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return pa.decoded_hex_str
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def generate_signal(messages: list, modulator: Modulator, snr_db: int, add_noise=True):
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result = []
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message_powers = []
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if isinstance(messages, Message):
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messages = [messages]
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for msg in messages:
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modulated = modulator.modulate(msg.encoded_bits, msg.pause)
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if add_noise:
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message_powers.append(np.mean(np.abs(modulated[:len(modulated) - msg.pause])))
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result.append(modulated)
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result = np.concatenate(result)
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if not add_noise:
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return result
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noise = np.random.normal(loc=0, scale=1, size=2 * len(result)).astype(np.float32).view(np.complex64)
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# https://stackoverflow.com/questions/23690766/proper-way-to-add-noise-to-signal
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snr_ratio = np.power(10, snr_db / 10)
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signal_power = np.mean(message_powers)
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noise_power = signal_power / snr_ratio
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noise = 1 / np.sqrt(2) * noise_power * noise
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return result + noise
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def generate_message_bits(num_bits=80, preamble="", sync="", eof=""):
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bits_to_generate = num_bits - (len(preamble) + len(sync) + len(eof))
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if bits_to_generate < 0:
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raise ValueError("Preamble and Sync and EOF are together larger than requested num bits")
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bytes_to_generate = bits_to_generate // 8
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leftover_bits = bits_to_generate % 8
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return "".join([preamble, sync]
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+ ["{0:08b}".format(random.choice(range(0, 256))) for _ in range(bytes_to_generate)]
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+ [random.choice(["0", "1"]) for _ in range(leftover_bits)]
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+ [eof]
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)
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def generate_random_messages(num_messages: int, num_bits: int,
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preamble: str, sync: str, eof: str, message_pause: int):
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return [
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Message.from_plain_bits_str(
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generate_message_bits(num_bits, preamble, sync, eof), pause=message_pause
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)
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for _ in range(num_messages)
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]
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